This invention relates to filter driers and more particularly to a bidirectional flow filter drier which is especially useful in heat pump systems or any other air conditioning or refrigerant systems where fluid flows may be reversed.
Bidirectional flow filter drier assemblies are well-known in these fields and provide convenient, economical devices which utilize a common filter drier medium and a minimum of interconnections with the plumbing of the system which is advantageous both from the standpoints of minimal original equipment and ease of maintenance and repair.
One particularly useful biflow drier is shown in Griffin, U.S. Pat. No. 4,954,252, which is owned by the assignee of the present invention. In the Griffin drier, a simplified and reliable biflow filter drier structure is provided which utilizes a minimal number of components. A valving structure in the filter drier is easily fabricated from punched metal parts and readily assembled by spot welding techniques. The valving structure includes a pair of identical check valve assemblies and a single molded desiccant core. The check valve assemblies are located at opposite ends of the core and each includes stainless steel reed-type flapper valves formed from a single sheet of material. While the Griffin drier structure is appropriate for many applications, the desiccant core provides both filtration and water removal functions, which can reduce the operational life of the desiccant. The desiccant in the core has small openings which can plug or clog, particularly on the surface of the core, and which may require frequent drier replacement.
As such, it is believed that there is a demand for a further improved bidirectional flow filter drier which has a structure where the desiccant core is not required to provide a filtration function, but which rather performs primarily a water-removing function and which thereby extends the useful life of the filter drier.